Introduction to Environmental Toxicology

Decline of Pollinators

• Decline in honeybees and other pollinators is a significant concern.
• Certain pesticides are identified as harmful, causing colony collapse disorder.
• Comparison to Silent Spring by Rachel Carson, highlighting the hazardous effects of DDT and synthetic pesticides.

Rachel Carson's Impact

• Silent Spring debated synthetic chemical use in the US.
• Message: Pesticides harm human health, wildlife, and ecosystems.
• Pesticides should be used conservatively, not abolished.
• Book serialized in The New Yorker, reaching a wide audience.

Historical Context

• Mid 1940s-1960s: Pesticides were widely used, untested for health impacts.
• DDT sprayed in public places, recommended for household use.
• Declines in bird populations traced to thinning eggshells due to DDT.
• Raptors affected severely by biomagnification.

Response to Silent Spring

• General public concerned about health effects.
• Pushback from industry, personal attacks on Carson.
• American Chemical Society and Monsanto attempted to discredit Carson.
• DDT nearly banned in the US by 1972.

Ethical Considerations

• Continued sale of DDT to nations dealing with malaria.
• Ethical dilemma: balance between DDT risks and malaria mortality.

Success of Carson’s Work

• Carson’s credibility as a USGS scientist and her accessible writing.
• Bridged scientific insights with public accessibility.

Environmental Toxicology Overview

• Study of toxic substances in the environment.
• Focus on effects on humans, wildlife, and ecosystems.
• Toxicity: Degree of harm inflicted by a substance.
• "Dose makes the poison"—importance of dosage in toxicity.

Misconceptions

• "Solution to pollution is dilution"—not always true.

Toxins vs. Toxicants

• Toxins: Natural poisons from living things (e.g., algae, snakes).
• Toxicants: Synthetic chemicals, focus of the course.

Ubiquity of Toxicants

• 2002 study: US streams contain wastewater contaminants.
• 2005 study: Newborns have synthetic chemicals in umbilical cord blood.

Classification of Toxicants

1. Corrosives: Destroy tissue (e.g., acids, bleach)
2. Asphyxiants: Deprive oxygen (e.g., carbon monoxide)
3. Carcinogens: Cause cancer (e.g., BPA, arsenic)
4. Mutagens: Cause DNA mutations (e.g., benzene)
5. Teratogens: Affect embryo development (e.g., thalidomide)
6. Allergens: Affect immune system (e.g., asthma triggers)
7. Neurotoxins: Impact nervous system (e.g., heavy metals)
8. Endocrine Disruptors: Interfere with hormones (e.g., atrazine)

Focus on Endocrine Disruptors

• Example of diluted chemicals causing significant harm.
• Underscore that dilution is not a solution to pollution.